There are many types of detergents which are employed for different applications. The physical forms of these detergents include various liquids, solids, and powders. High performance detergents such as mechanical warewashing detergents, must meet end use criteria. Therefore certain physical forms may be required. With certain detergents, it is desirable to have a paste or a solid detergent as opposed to a powder or a liquid.
Formation of liquid detergents is generally not difficult since the components can be easily mixed to form the end product. Although there are many complex variations, powdered detergents can be formed by simply mixing the granular detergent components together. These, however, are unsuitable for many applications. Liquid detergents may not have sufficient concentration to perform the function required. Powdered detergents are difficult to dispense in a uniform manner due to the variable rates of solution of the components, settling and so on.
Solid and paste detergents can be used to overcome the problems encountered with liquids and powders. However, these are more difficult to produce and solids have several arguable disadvantages. Solids can be formed by simply compressing granular detergents together. However, these are unsuitable for many applications due to the irregularity in the rate of dissolution of the components as well as the strength of the product.
Solid and paste detergents can be formed by combining hydratable detergents with water. The viscosity increases by hydration of the detergent components or the use of thickeners. If a sufficient concentration of hydratable detergent is added, the detergent solidifies.
With this hydration process, the components can actually set in the mixing vessel which requires an inordinate amount of time and effort to clean. Further, hydration is generally an exothermic reaction. When detergents are formed and their viscosity increases due to hydration, a great deal of heat must be dissipated.
In many applications, heat must even be added and then removed from the system. For example, Fernholz U.S. Pat. No. RE 32,818 discloses supersaturating an aqueous solution with hydratable detergent compositions under elevated temperatures to permit formation of a settable detergent. This is an extremely inefficient method of manufacturing a detergent. The requirement that the detergent be heated initially requires an expenditure of energy. Further, it must be maintained in an elevated temperature until dispensing. After dispensing a great deal of heat again must be removed from the formed detergent.
Solid detergents formed by the method disclosed in the Fernholz patent also have significant use disadvantages. They are generally used by spraying water against the solid detergent to dissolve the detergent. As the detergent dissolves, chunks can break off and interfere with the operation of the warewashing machine. Further, as it dissolves, due to a decrease in size and the rate of dissolution, the concentration of the detergent composition be too low to meet use requirements.
There are other patents which discuss formation of solid detergents such as Heile U.S. Pat. No. 4,680,134, Gansser U.S. Pat. No. 4,753,755, Olson U.S. Pat. No. 4,681,914, Davis U.S. Pat. No. 4,808,236, and Copeland U.S. Pat. No. 4,725,376.
Paste detergents do not suffer from many of the problems associated with the manufacture and use of solid detergents. Sabatelli U.S. Pat. No. 4,147,650 discloses several paste detergents that have particularly strong, self-supporting structures. Further, Bruegge U.S. patent application 171,759, filed Mar. 22, 1988 and Bruegge U.S. Pat. No. 4,681,696 disclose paste detergents. None of these provide a simple easy method of forming a highly viscous paste detergent.